import numpy as np
from math import log,exp

t=[1,2,4,8,16,32,64]
W=[4.22,4.02,3.85,4.59,3.44,3.02,2.59]

t_in=float(input())

def cal_ln(lst):
    new_lst=[]
    for i in lst:
        new_lst.append(log(i))
    return new_lst

def phiCal(x,n):
    lst=[]
    for i in x:
        lst.append(i**n)
    return lst

y=cal_ln(W)
x1=cal_ln(t)
x0=phiCal(x1,0)

x=(x0,x1)


def itemCal(lst1,lst2):
    sum=0
    for i,j in zip(lst1,lst2):
        sum+=i*j
    return sum

A=np.zeros(shape=(2,2))
for i in range(2):
    for j in range(2):
        A[i,j]=itemCal(x[j],x[i])


b=[itemCal(y,x0),itemCal(y,x1)]

a=np.linalg.solve(A, b)

ans=a[0]+a[1]*log(t_in)
ans=exp(ans)

print("%.4f"%ans)

import matplotlib.pyplot as plt
plt.plot(x1,y)
plt.show()